@VUM,
Thanks for the youtube link. I did find a youtube video for the Nissan note which was similar.

@Vexorg,
Yes I agree with you it seems a silly design.

Not sure what a Nissan dealership would charge for a fully service including the plug change but I have no intention of paying that, even doing it yourself the total cost of genuine spark plugs + gasket is not exactly cheap.
The only good news is the large number of miles the plugs can do until the next change.

Hi. The actual cost of plugs vary from where you buy from , I recently had mine done mechanic said nightmare to do .Dealer wanted £70
After a quick search I got them for £38 NGK with postage .So really not that expensive as you won't be changing them years